The present invention relates generally to loudspeakers, and, more particularly, to an apparatus and a related method for producing sound from a panel in a cabin-like environment.
Speakers are used in a wide variety of environments. While some environments are conducive to placing speakers appropriately for maximized sound quality, other environments such as vehicle interiors typically place constraints on speaker location, size and shape. In such environments, a common solutions is to mount small speakers in less than optimal locations, to the detriment of sound quality.
Typical loudspeaker systems for automobiles include two conventional speakers that are either mounted facing inward in the lower front door panels, or mounted facing upward in the dashboard. Additionally, two conventional speakers are mounted facing upward in the rear panel, facing upward to the rear window.
Door panel speakers that face inward directly toward passengers in the car are generally preferable. However, they necessarily must have a small size to fit within the limited confines of a door panel. Additionally, they typically direct sound toward the legs of occupants in the front seats, which reduces sound quality. Additionally, such speakers are generally difficult to hear from the rear seats.
There is generally more room for dashboard and rear panel speakers because they can extend out of the passenger cabin into the engine compartment or trunk area, and thus such speakers are often not as restricted in size as the door panel speakers. However, their sound is reflected from the front and rear windows, respectively, which adversely affects sound quality. Additionally, all of the above-listed speaker locations are substantially more appropriate for some occupants"" listening pleasure than for others, leading to difficulties in providing reasonable lateral and fore-and-aft balancing of the sound for multiple occupants.
An alternate form of a loudspeaker known as a planar diaphragm loudspeaker is known for providing high quality sound from a camouflaged location in residential or commercial building. The diaphragm of such a loudspeaker is typically formed by a relatively stiff and substantially planar diaphragm that may be supported by a frame around the edges of the diaphragm. An electromagnetic driver, in the form of a voice coil assembly, is coupled to the rear surface of the diaphragm, and is also mounted to the frame. The voice coil or driver presses on a circular plate called a hammer, which, in turn, vibrates the diaphragm at acoustic frequencies to produce sound.
Typically, the planar diaphragm is constructed of a preexpanded cellular plastic material, such as polystyrene or STYROFOAM(copyright). The front, visible side of the diaphragm is flat, and may be disguised as a ceiling tile or section of wall. The rear of the diaphragm, where the voice coil or driver is mounted, while generally planar, has a specific contour to improve the sound quality of the loudspeaker. These types of loudspeakers are well suited for architectural use in ceilings and walls, where there is adequate space to mount a large flat panel of reasonable size. Such loudspeakers, while highly advantageous for architectural use, would typically suffer many of the same size disabilities as conventional speakers if installed in a vehicle cabin. In particular, good planar diaphragm loudspeakers would require both adequate surface area for the diaphragm and adequate depth for the voice coil.
Accordingly, there has existed a need for an improved loudspeaker, and a related method, to provide high quality omni-directional sound reproduction in an environment having structural limitations due to imposed structural constraints, such as in a vehicle cabin. The present invention satisfies these and other needs, and provides further related advantages.
The present invention provides a loudspeaker, and a related method for producing sound, which is particularly suited for use in cabin-like environments having structural limitations due to imposed constraints and/or for use in environments requiring the sound to be focused on individual listeners.
Embodiments of the loudspeaker of the invention can include an generally planar acoustic panel, a voice coil driver, and a transmission member extending between an edge of the acoustic panel and the voice coil driver. The transmission member conducts the vibrational energy from the voice coil driver to the acoustic panel. The voice coil driver is configured to drive the acoustic panel so as to excite the acoustic panel in various acoustic modes of vibration.
Advantageously, some preferred embodiments of the loudspeaker can be incorporated in a vehicle, where the vehicle""s body is equipped with an enclosure forming a cabin interior. The loudspeaker""s acoustic panel is incorporated into the enclosure such that its sound radiating surface forms part of an inner surface of the enclosure, while the transmission member extends outside of the cabin to avoid structural limitations within the cabin.
Other embodiments of the loudspeaker of the invention can include an acoustic panel having a curvature between two ends, where one end is supported, and also a voice coil driver configured to drive the acoustic panel along an edge at the other end of the acoustic panel. The voice coil driver is thereby configured so as to flex the acoustic panel along its curvature and excite the acoustic panel in various modes of vibration at acoustic frequencies.